Let f(x)=xnsin(1/x)f(x) = x^n \sin(1/x)f(x)=xnsin(1/x) for x≠0x \neq 0x=0 and f(0)=0f(0)=0f(0)=0. For what integer nnn is fff differentiable at x=0x=0x=0?
n=0n = 0n=0
n=1n = 1n=1
n>1n > 1n>1
n≥1n \geq 1n≥1